C++ code to find BSSID OF associated network

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Want to know the ESSID of wireless network via C++ in UBUNTU

Hello I have written the following code which is a part of a project. It is used to find the ESSID of the current associated network. But it has a flaw that it also the displays the ESSID of the network with which I am not associated i.e. if I try to associate myself with a wireless n/w and if it is unsuccessfull i.e. NO DHCP OFFERS ARE RECEIVED, then also it will display the that ESSID with which I have made my attempt.

Is it possible to find the BSSID of current associated wireless network as it is the only way with which I can mark b/w associated and non associated, e.g. with an ioctl call?

int main (void)
{
    int errno;
    struct iwreq wreq;

    CStdString result = "None";

    int sockfd;
    char * id;
    char ESSID[20];
    memset(&wreq, 0, sizeof(struct iwreq));

    if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        fprintf(stderr, "Cannot open socket \n");
        fprintf(stderr, "errno = %d \n", errno);
        fprintf(stderr, "Error description is : %s\n",strerror(errno));
        return result ;
    }
    CLog::Log(LOGINFO,"Socket opened successfully");

    FILE* fp = fopen("/proc/net/dev", "r");
    if (!fp)
    {
        // TBD: Error
        return result;
    }

    char* line = NULL;
    size_t linel = 0;
    int n;
    char* p;
    int linenum = 0;
    while (getdelim(&line, &linel, '\n', fp) > 0)
    {
        // skip first two lines
        if (linenum++ < 2)
            continue;

        p = line;
        while (isspace(*p))
            ++p;

        n = strcspn(p, ": \t");
        p[n] = 0;

        strcpy(wreq.ifr_name, p);

        id = new char[IW_ESSID_MAX_SIZE+100];
        wreq.u.essid.pointer = id;
        wreq.u.essid.length = 100;
        if ( ioctl(sockfd,SIOCGIWESSID, &wreq) == -1 ) {
            continue;
        }
        else
        {
            strcpy(ESSID,id);
            return ESSID;
        }
        free(id);
    }

    free(line);
    fclose(fp);
    return result;
}

score 0 · Answer 1 · answered May 13 '11 at 16:12

Note: Since this question seems to be duplicated in two places, I'm repeating my answer here as well.

You didn't mention whether you were using an independent basic service set or not (i.e., an ad-hoc network with no controlling access point), so if you're not trying to create an ad-hoc network, then the BSSID should be the MAC address of the local access point. The ioctl() constant you can use to access that information is SIOCGIWAP. The ioctl payload information will be stored inside of your iwreq structure at u.ap_addr.sa_data.

C++ code to find BSSID OF associated network

1 Answers1